New receiver

I pretty much concur along lines of Rlwainwright. Separates, yes, would be strongest sounding/performing option, sonics wise. Better amplifier with separates, like 95% of the time, by default - weak amps in ESPECIALLY lower priced AVR's. If not, then get the AVR and consider adding an outboard amp to that mix with AVR that has Pre-out's. If you can't - or don't want to - go with multiple boxes, and stay AV receiver all-in-one, then I suggest the most features, DEFINITELY WITH A ROOM EQ, 4K pass, 3D, switching, Bluetooth, connectivity, whatever, you can find in an AVR. Used market and refurb (warranty?) gets you MUCH more bang for buck, as this stuff depreciates down to $0.10c on the dollar from MSRP like nobody's business!! Believe it! Buy new, and you'll get less, weaker amps, and less power for your dollar (although lots of features for money these days, regardless, minus preout's) .
That all said, either way, I'd strongly recommend a warmer sounding receiver (crossed over to 100-80hz to a sub) and or amplifier in the mix, to balance the slightly cool somewhat analytical yet clear sonic character of Deftech's, such as Denon, NAD, Onkyo, Integra, Sherwood, and such for AVR's. For amplifiers, consider used Parasound, Classe, NAD, Integra, Sony ES, Outlaw(?), Bryston, etc, and similar, with warmer more forgiving tonality.
Million choices and directions. I'd prob steer away from Yamaha, Pioneer, cheaper Marantz, and even the otherwise superb HK's with your Deftech's, if I had to guess. Anthem?..might be tick bright, but then maybe not. Otherwise top tier AVR with EQ and refinement.
That's my experience of playing with this stuff for decades now. Some pieces may vary of course.
I'd recommend the

.... otherwise very good sounding Arcam, NAD, and B&K receivers but, again, NO EQ feature! (basically all rooms have bass problems you'll not fix from 20hz -300hz, and REQUIRE EQ'ing, PERIOD! ..too invaluable to pass up for hi-fidelity, IME).
You (he??) doesn't need 7.1 or Atmos, etc? Any 5.1-7.1 that fit on the list, are worth investigating, find reviews, or must give a try or sell if don't work out for you. Ok, I'm done now. ..

I have a Denon Avr 3100 and love it.

The all in one box feature is for this guy. A couple of people have recommended Denon either the 4200 or 4100 or the 3100 series. Seems like they are all pretty similar. Higher numbers more power and better Audessey and now HDCP 2.2. Do we need this? How do the Denons stack up against the competition. Thanks for all of the responses.

Denon used to have better quality control at lower price points, IME. But Denon's overall stand-alone sound quality is still a pinch better At all price points, though. What you do get is more amplifier power and features on Onkyo's, dollar per dollar.
If however, I was buying off shelf today at $1000, I'd say I'd probably still have to get the Onkyo. (wow I can't believe I said that! ..I'm disappointed in you Denon!)

For the record, Just stating, that a few years old HK or Yamaha AVR with features needed, add some used Parasound HCA1205a 5 ch power amp - all for $1000 range, used, total - and would most definitely stomp on the sound quality of the $1000 stand-alone AVR, new!!! Yup, pretty much hands down. Just saying... I'd rather have superior sound quality/performance, myself.

$1000 new Denon/ONkyo = 6-7/10 sound quality,all considered
$500 (used) AVR(w EQ)+amp = 8-8.5/10 sound quality